Needle-bar actuating mechanisms for sewing machines



I ril 2 1959 A. s. MELOY, JR, ET AL 2,883,952

NEEDLE-BAR ACTUATING MECHANISMS FOR SEWING MACHINES Filed 001;. 3, 1956 2 Sheets-Sheet 1 Fug. I.

I I2 INVENTOR.

' Ar/hurS. Me/oy Jr.,Ray 0. Sweet and i B Walter G.- Johnson. W ATTORNEY 2 Sheets-Sheet 2 IN VEN TOR.

Arthur S Me/oyJr, Ray 0 Sweet and BY Wa/Ier 6. Johnson.

TTORNEY April 28, 1959 A s. MELOY, JR.. ETAL NEEDLE-BAR ACTUATING MECHANISMS FOR SEWING MACHINES Filed Oct. 5, 1956 .HHHH Ii HUHHH -i I u 2 m a All! United States Patent NEEDLE-BAR ACTUATING MECHANISMS FOR SEWING MACHINES Arthur S. Meloy, Jr., Stratford, and Ray D. Sweet and Walter G. Johnson, Bridgeport, Conn., assignors to The Singer Manufacturing Company, Elizabeth, N.J., a corporation of New Jersey Application October 3, 1956, Serial No. 613,778

2 Claims. (Cl. 112221) With the above and other objects and advantages in view as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

Fig. 1 represents a vertical cross-sectional view ofv the sewing head portion of a sewing machine having this invention applied thereto,

Fig. 2 represents a left-end elevational view of the sewing head portion of a sewing machine illustrated in Fig. 1 with the end cover plate and the thread take-up device removed.

Referring to the drawings, this invention is illustrated as applied to a sewing machine having a conventional type of frame of which only the hollow sewing head portion 11 is illustrated. It will be understood that the sewing head of a sewing machine frame comprises the free extremity of a bracket-arm which extends above the fabrics to be stitched and provides support for a sewing needle 12 and the various needle thread controlling and manipulating devices which will be hereinafter described.

The needle is secured by means of a set screw 13 in a needle clamp 14 carried at the lower extremity of a tubular needle-bar 15 journaled in bushings 16, 17 carried in the sewing head. Clamped on the needle-bar between the bushings 16, 17 by means of a split collar 18 and a clamp screw 19 is a pivot pin 20 which extends at right angles to the needle-bar and which is preferably made hollow by an axial bore 21. At its free extremity the pivot pin 20 is embraced by a slide block 22 disposed in a channeled guide member 23 fixed, as by screws 24, to the inside wall of the sewing head, thus to prevent the needle-bar from turning and constrain the needle-bar to endwise reciprocatory movement in .the bushings 16, 17.

The needle-bar is actuated from a main drive shaft 26 journaled in bearings, such as the ball bearing 27, fixed in the sewing head. Secured to the main drive shaft by a set screw 28 is a crank member formed with a crank arm 29 and with a counterweight 30 which will be described more fully hereinbelow. The crank arm 29 is formed with a split bore 31 and provided with a clamp screw 32 by which a crank pin 33 is secured in the crank arm. Iournaled on the crank pin 33, with needle bearings 34 interposed therebetween, is a needlebar driving link 35 which at its lower extremity pivotally embraces the pivot pin 20 extending from the needle bar. A bearing bushing 36 is preferably interposed between the needle-bar driving link 35 and the pivot pin 20. The crank pin 33 is formed to extend on both sides of the needle-bar 15 and as illustrated in Fig. 2, the crank pin is formed on the opposite side of the needle-bar from the counterbalance 30 with an enlarged head portion 38 provided with an arcuate tang 39 adapted to accommodate a circular base plate 40 upon which a rotary needle thread take-up member 41 is secured. The center of mass of the rotary needle thread take-up member is preferably disposed substantially coincident with the axis of rotation of the main drive shaft 26. The take-up illustrated in the drawings is of the type disclosed in the U. S. Patent No. 2,636,464, April 28, 1953 of Van Wagener et al. to which reference may be had for a more complete description thereof.

The sewing head 11 is closed by a sheet metal end cover plate 42 which fits snugly about the circular base plate 40 of the take-up member. As indicated at 43, a take-up guard device is secured to the end cover plate.

In the needle-bar actuating mechanism of this invention, the needle-bar driving link 35 takes a unique form in that it is provided with an extension 45 on that side of the pivotal connection of the link with the crank pin 33 which is opposite that of the pivotal connection of the link with the pivot pin 20 on the needle-bar. The extension 45 of the needle-bar driving link provides a counterweight which serves to shift the mass center of the needle-bar driving link 35, the pivot pin 20, the needle-bar 15, needle clamp 14 and the needle 12 into substantial coincidence with the centerline of the crank pin 33. When thus counterbalanced, the needle-bar driving link 35 and all of the parts which move in response to movement of the link become the equivalent, insofar as distribution of mass is concerned, to a single mass located symmetrically about the crank pin 33. The needle-bar actuating connections, which are usually the source of considerable unbalance in a sewing machine, are thus resolved into the equivalent of a continuously rotating mass centered about the crank pin 33. The entire needle-bar actuating mechanism including the crank mechanism 29, 33 can then be balanced by the counterweight 30 on the crank member, with the counterweight 30 made to counterbalance not only the crank arm 29 and the crank pin 33 but also the resultant mass of the needle-bar driving link 35 with its counterbalance arm 45 and the mass of all of the parts which move in response to movement of the link. With the system counterbalanced as described above, the entire mass of the needle-bar mechanism is resolved into the equivalent of a continuously rotating mass centered about the axis of rotation of the main drive shaft 26.

Particularly in high speed sewing machines, it is essential that the needle-bar mechanism be housed completely within the machine frame. That is, an exposed moving part would endanger the safety of the machine operator, lubricant spray would be objectionable if any of the moving elements were to be exposed, and the introduction of foreign matter into the vicinity of the moving parts would increase the wear at the various bearing points. In order that the counterweight provided by the counterbalance arm 45 of the needle-bar driving link may be accommodated within the confines of the hollow sewing head 11 having reasonable dimensions, the arm 45 is formed with an aperture 46 within which an insert 47 is fitted. Preferably the insert 47 is made of a material having a density greater than that of the material of which the needle-bar driving link is fabricated. The driving link 35, the pivot pin 20 and the needle-bar on the other hand are made as light as is possible in order to reduce the total mass required to be counterbalanced. A reduction in weight of the needle-bar and pivot pin is accomplished by their hollow tubular construction. A reduction in weight of these parts may also be made by fabricating the parts of aluminum or other light materials.

The counterweight insert 47, which is preferably made of lead or other relatively dense material, is secured in place in the aperture 46 by a pin 48. The counterweight insert is preferably formed with an offset extension 49 which occupies a position on the same side of the needlebar driving link as that on which the needle-bar is disposed. It will be noted that the needle bar bushings are both disposed beneath the level of the crank pin 33 and that the needle-bar is preferably arranged such that when the needle-bar is at the bottom of its stroke, the top of the needle-bar will be disposed beneath the level of the crank pin 33 and consequently out of the path of the laterally offset portion 49 of the counterweight. With this construction, a compact arrangement of the counterweight is achieved which is accommodated readily in the limited space available within the hollow sewing head.

Having thus set forth the nature of this invention, what is claimed herein is:

1. In a sewing machine having a frame including a hollow head, a drive shaft journaled in said frame and extending into said hollow head, crank means carried for rotation with said drive shaft and disposed within said hollow head, bearing means carried within said hollow head and disposed beneath said crank means, a needle-bar journaled for endwise reciprocatory movement in said bearing means, a needle clamp carried by said needle bar, and a needle disposed in said clamp, a needle-bar driving link journaled on said crank member and disposed at one side of said needle-bar, means piv otally interconnecting said driving link with said needlebar, said needle-bar driving link being formed with an arm extending on the opposite side of said crank pin from the means pivotally interconnecting said driving link with said needle-bar, and a counterweight secured to said driving link arm to position the combined mass center of the counterweight, needle heir driving link, pivotal interconnecting means needle bar, needle clamp, and needle substantially coincident with said crank pin, said counterweight extending beyond that side of said driving link occupied by said needle-bar, said needle-bar being disposed when in one extreme position of reciprocation entirely beneath said counterweight.

2. In a sewing machine having a frame including a hollow head, an actuating shaft journaled in said frame and extending into said hollow head, bearing means provided in said hollow head below the level of said actuating shaft, a needle-bar journaled for endwise reciprocatory movements in said bearing means, needle-bar reciprocating crank means secured to said actuating shaft within the confines of said hollow head, said crank means including a counterbalance arranged at one side of said needle-bar, and a crank-pin disposed transversely of said needle-bar and extending on both sides thereof, a rotary thread take-up member secured to said crank-pin at the opposite side of said needle-bar from said counterbalance and disposed to act upon the needle thread, the center of mass of said rotary thread take-up member being disposed substantially coincident with the axis of said actuating shaft, a needle-bar actuating link disposed at one side of said needle bar, means journaling said needle bar actuating link on said crank-pin, means pivotally connecting said needle bar actuating link to said needle-bar, and a second counterbalance secured to said needle bar actuating link at the opposite side of said crank-pin from the connection of said needle-bar actuating link to said needle-bar, said second counterbalance projecting from said needle-bar actuating link and extending over said needle-bar.

References Cited in the file of this patent UNITED STATES PATENTS 1,020,057 Ringe Mar. 12, 1912 1,664,942 Pope Apr. 3, 1928 FOREIGN PATENTS 856,989 Germany Nov. 27, 1952 

